In '98, I believe, my now hiking buddy and one of his friends went into the same basin I've been investigating since 2014 where we've had any number of things happen. They camped at the highest significant lake, about 6400 feet. They had a camp visit, wasn't confrontational or anything like that. A group, exchanging mumbly vocals, crossed the edge of the camp site. Most stayed there, one broke away and came over to their tent pressing inwards on the fabric. The dog, think it was the other guy's dog, went to the bottom of a sleeping bag whimpering and wouldn't come out 'til mid morning. This was a dog that'd been used to track and tree bears, not a coward, but after that night, it was BROKEN. From that day forward it wouldn't go outside in the dark to pee in its own yard .. in town. Whatever happened to it, it was something seemingly more terrifying than mere death because it'd faced that countless times chasing bears.
My guess ... infrasound. It's only a guess.
MIB